Landing wheelie bug report.

[Stormenson 1]

True .If there are strong wings this bug is very annoying. Because it is possible to gain speed after the first hop on touchdown. 

[serviceceiling 135]

14 hours ago, kwstakis1312 said:

True .If there are strong wings this bug is very annoying. Because it is possible to gain speed after the first hop on touchdown. 

It's not even a hop. I once did a testflight where I experienced this bug, so I went to outside view and the gear was still in "air mode" - so stil just hanging like it would be in the air. The plane was then floating along like on a magic energy cussion lol. 

[Captain Kevin 586]

On 5/27/2018 at 11:16 AM, downscc said:

If you fly the aircraft properly during landing this should not be a problem.  Landing too fast is a problem.

I've seen this issue before, and it certainly isn't a result of landing too fast. If anything, by the time I'm about to touch down, I'm actually going too SLOW. That being said, it's always been hit or miss when it happens, so I've never been able to figure out why it does.

[viperlid 3]

Evening gents

Im experiencing this exact issue in the 747-8F as im writing this. anyone else had experienced this in the -8 version?

 

regards

Alfredo Hernandez

[harvester21 34]

I had it on arrival to OOMS yesterday, and have had it from time to time before. I am also not sure what causes it and so far I have not been able to find the conditions required to replicate it. When I do I will most certainly open a ticket.

[jgoggi 65]

I thought this would be fixed with the latest updates...

[Captain Kevin 586]

15 hours ago, jgoggi said:

I thought this would be fixed with the latest updates...

Did they ever figure out what was causing it in the first place?

[BlueStar 323]

A similar thing happen landing to the east in PANC about two in the morning a few years back. Pasted 30 and hadn't even started to slow down. Braking had been reported as medium to poor, closer to nil.  No wheelie involved. ROFL.

Grace and Peace, 

 

[rsrandazzo 6,353]

Gents,

We have not found a replication case for this in house so it hasn't been resolved.  Things have calmed down a bit so perhaps i'll find some time to see if I can't capture it in the debugger in the coming weeks.  We will see...

 

[rsrandazzo 6,353]

On 10/26/2018 at 4:13 AM, harvester21 said:

I had it on arrival to OOMS yesterday, and have had it from time to time before. I am also not sure what causes it and so far I have not been able to find the conditions required to replicate it. When I do I will most certainly open a ticket.

Sander,

If it happens again, hit the pause key the moment you become aware of it.  Then give me the following items:

1) Airport and Runway being used.

2) Wind direction and speed.

3) Weather engine being used.

4) Nose pitch as read from the attitude indicator.

5) Roll as read from the attitude indicator.

6) RadAlt as read from the attitude indicator.

Might not lead me anywhere- but who knows. 

[harvester21 34]

Hi Robert,

Will report back with the above information next time it happens.

Thanks for the response!

Kind regards,

[Qavion2 39]

Did you accidentally activate Pogo Stick power after you turned off the engines ?? 🤔

Off topic, but I noticed a few other curiosities in that video clip:

Should the PFD and ND blank after switching off the engines? Wouldn't Standby Power take over almost immediately? The Upper EICAS seemed ok.

Shouldn't there be an [RA] flag on the PFD with no main bus power to the Radio Altimeters?

Should there be an [FD] flag on the PFD? I'm not sure how it would behave with the MCP unpowered.

Should the heading cursor be in view on the ND? The MCP is dead, so no computed data.

Shouldn't the Brake Pressure Gauge be showing fully zero (power normally comes from the Ground Service Bus)?

 

Unfortunately, I can't test this on the real aircraft anymore.

 

 

[kevinh 409]

On 10/27/2018 at 6:04 PM, rsrandazzo said:

Sander,

If it happens again, hit the pause key the moment you become aware of it.  Then give me the following items:

1) Airport and Runway being used.

2) Wind direction and speed.

3) Weather engine being used.

4) Nose pitch as read from the attitude indicator.

5) Roll as read from the attitude indicator.

6) RadAlt as read from the attitude indicator.

Might not lead me anywhere- but who knows. 

Robert,

I've been trying some tests at KEDW in the 748 and was able to replicate the effect the OP saw. Weather and wind are not part of the cause. I was using P3D default clear skies. The primary issue is that ground spoilers have no effect on lift or drag at touch down. Also, there is no apparent increase in drag with the nose held high. It's easiest to see the effect if wheel brakes are not used, so the only other drag is from ground friction. If you touch down normally at Vref and try and hold the nose up there is enough lift to take off again (as long as airspeed is still above stall speed). Before lift off occurs, as rad alt increases towards zero, airspeed also increases by a few knots. I assume this is due to ground friction reducing to zero. On a long runway you can repeat this cycle several times.

If you land normally, putting the nosewheel down, the airspeed trend vector is unaffected by ground spoilers. Deceleration should increase markedly with ground spoilers extended. Again, it's easiest to see this with no braking or reverse thrust.

The ground spoilers should also reduce lift. This would force the aircraft down on its wheels and prevent lift off even with airspeed above stall speed. As lift isn't reduced the aircraft is well above stall speed at touch down and still ready to fly.

[Jet_Pack2 0]

Hello everyone,

I experienced the same landing gear physics glitch today. Since I haven't been aware of this thread before I can't precisely answer all of the questions by rsrandazzo. (Sorry)

1) Airport was default KLAX, runway 06R

2) weather preset was clear, that probably also sets wind to calm

3) active sky installed but was not running, weather preset clear sky was loaded before the flight started

4) pitch on landing was pretty much normal, maybe a touch too nose high

5) roll was near zero

6) touch down was with 0 ft RA

additional info:
- before starting the flight I entered 0 fuel, 0 passengers, 0 payload from within FSX default fuel menu, so the aircraft was extremely light
- inside the aircraft I used the FMS menu option to set 20% fuel before the takeoff. I did not make any other entries in the FMS before the departure, did not set any departure runway, pretty much just set flaps and took off.
- flew one rather large pattern, 
- gnd spoilers were armed, autobrake was armed and set to 1.
- approach was performed with ap off, FD off, athr on
- athr was shown as SPD for some time but at some point the FMA for the speed went blank
- thrust was not automatically retarded on flare, I assume I disengaged athr at somepoint during the approach by accident
- manually idled the engines for the flare, heard spool down, eicas confirmed idle EPR
- did a very smooth touch down
- the spoilers did not extend
- upon gear compression the aircraft gained speed
- extra speed caused aircraft to lift off again
- in the air speed decreased again, causing the aircraft to touch down again
- again spoilers did no deploy
-> repeated about 3x before I started a recording.
Elevator was moved to neutral position upon touch down

During the recording you can see that at some point I played a bit with the elevator. A nose down input eventually caused the ground spoilers to extend. (well past the end of the runway)
Autobrake did not engage, probably because I wasn't on ground long enough.
Even with extended spoilers, which should cause a significant decrease in lift, the aircraft still managed to do several bounces with ease. But to be fair the ground started to get rough that far beyond the threshold.
Eventually I had enough and cut the engines. It still continued to roll for a while but eventually it got under 100kts and stayed down.

 

Regards,
Jan

Edited December 15, 2018 by Jet_Pack2

[ph-cxz 28]

14 minutes ago, Jet_Pack2 said:

Hello everyone,

I experienced the same landing gear physics glitch today. Since I haven't been aware of this thread before I can't precisely answer all of the questions by rsrandazzo. (Sorry)

1) Airport was default KLAX, runway 06R

2) weather preset was clear, that probably also sets wind to calm

3) active sky installed but was not running, weather preset clear sky was loaded before the flight started

4) pitch on landing was pretty much normal, maybe a touch too nose high

5) roll was near zero

6) touch down was with 0 ft RA

additional info:
- before starting the flight I entered 0 fuel, 0 passengers, 0 payload from within FSX default fuel menu, so the aircraft was extremely light
- inside the aircraft I used the FMS menu option to set 20% fuel before the takeoff. I did not make any other entries in the FMS before the departure, did not set any departure runway, pretty much just set flaps and took off.
- flew one rather large pattern, 
- gnd spoilers were armed, autobrake was armed and set to 1.
- approach was performed with ap off, FD off, athr on
- athr was shown as SPD for some time but at some point the FMA for the speed went blank
- thrust was not automatically retarded on flare, I assume I disengaged athr at somepoint during the approach by accident
- manually idled the engines for the flare, heard spool down, eicas confirmed idle EPR
- did a very smooth touch down
- the spoilers did not extend
- upon gear compression the aircraft gained speed
- extra speed caused aircraft to lift off again
- in the air speed decreased again, causing the aircraft to touch down again
- again spoilers did no deploy
-> repeated about 3x before I started a recording.
Elevator was moved to neutral position upon touch down

During the recording you can see that at some point I played a bit with the elevator. A nose down input eventually caused the ground spoilers to extend. (well past the end of the runway)
Autobrake did not engage, probably because I wasn't on ground long enough.
Even with extended spoilers, which should cause a significant decrease in lift, the aircraft still managed to do several bounces with ease. But to be fair the ground started to get rough that far beyond the threshold.
Eventually I had enough and cut the engines. It still continued to roll for a while but eventually it got under 100kts and stayed down.

 

Regards,
Jan

Because you turned off the flight director you can’t read the fma which tells you your speed information. Secondly you are flaring too high only a 2 degree nose up in necessary.